This invention relates to the use of prepayment mechanisms for alternative energy supply systems and to a system to monitor remotely connected devices and ancillary equipment, particularly those forming part of alternative energy supply systems.
A distinction should be drawn between alternative and renewable energy resources, the latter being a term that is often used incorrectly as being synonymous with the former. For example, large scale hydro-electric power generation, whilst utilising a renewable energy source, qualifies as a conventional form of energy supply, while small scale hydroelectric power generation in the form of a water wheel, for instance, is readily classifiable as an alternative form of energy supply. In the kinds of alternative energy supply systems contemplated by this invention, the energy generated by the system is applied directly to a single point of use or a small number of points of use. These systems are normally small, standalone systems or, at most, small community based systems that utilise available resources to generate energy.
Alternative energy supply systems are often regarded as a supply of "free" energy, but in reality they are nothing of the sort, bearing in mind the capital cost of the equipment and the cost: of maintenance. The need exists, in consequence, to control the use of such systems, preferably in proportion to the use of the system and the consumption of the energy provided by the system. However, it is typical of such alternative energy supply systems that the energy consumer exercises direct control over both the generation and the supply of the energy. This makes it more difficult to introduce practical control and payment mechanisms, such as the prepayment mechanisms frequently used to control the dispensing of utilities, such as gas, electricity and water. However, French Patent No. 2 689 333--Transenergie SA--describes a relatively simple prepayment system for alternative energy supplies. This system is loaded with credit by exchanging a removable control box for a new box with consumption credit loaded.
Allied to the above difficulties are the problems posed by theft and vandalism of this type of equipment. In the nature of these systems, they will be used in remote or inaccessible locations where they are vulnerable to abuse. Very often, the components of the system are useful on their own. This makes the equipment even more prone to theft and, while it is known to use protective housings to guard against theft, it might still be possible for a thief to remove components of the system for use in conjunction with other equipment.
South African Patent No. 97/1249--Amic Industries Limited--describes a security system that might be useful in guarding against this danger. This security system relies on the continuing integrity of a collection made up of a number of items, for instance a number of valuable appliances in a home. If one or more of the items is removed from the collection, this would constitute an alarm condition. The collection is defined by fitting a reporting device to each monitored item and including the item in the monitoring group of a monitoring device adapted periodically to detect the presence or absence of the reporting devices fitted to the items in the group.
Another approach to solving this problem is suggested by South African Patent No. 97/1105--Amic Industries Limited (and the patent applications related thereto:--United Kingdom Patent Application No. 97 02902.9 and German Patent Application No. 187 05 534.6). These applications describe a monitoring system for items of movable property. The monitoring system incapacitates the item by rendering the item useless if the item is not returned to a home base or its place of storage within a predetermined time.